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Hess's Law

Q. Calculate the standard enthalpy change for the following chemical equation. 2HCl(g) + F2(g) → 2HF(l) + Cl2(g) Use the following thermochemical equations to solve for the change in enthalpy. 4HCl(g) + O2(g) → 2H2O(l) + 2Cl2(g) ΔH° = -202.4 kJ 1/2H2(g) + 1/2F2(g) → HF(l) ΔH° = -600.0 kJ H2(g) + 1/2O2(g) → H2O(l) ΔH° = -285.8 kJ

Solved • Nov 19, 2019

Hess's Law

Q. Nitric acid can be manufactured in a multi-step process, during which nitric oxide is oxidized to create nitrogen dioxide. 2NO(g) + O2(g) → 2NO2(g) Calculate the standard reaction enthalpy for the above reaction using the following thermodynamic data. N2(g) + O2(g) → 2NO(g) ΔH^+1 = 180.5 kJ N2(g) + 2O2(g) → 2NO2(g) ΔH^+2 = 66.4 kJ a) -114.1 kJ b) -100.3 kJ c) -252.4 kJ d) -246.9 kJ

Solved • Nov 19, 2019

Hess's Law

Q. Calculate the Δ Hrxn for the reaction: A + 2B → 3C + 2D + 3E Knowing that: 3C + 2D + 3E → A + 2B Δ Hrxn = 17.8 kcal

Solved • Nov 14, 2019

Hess's Law

Q. Data: 2Fe(s) + O2(g) => 2FeO(s) ΔH = -545.8 kJ 4Fe(s) + 3O2(g) => 2Fe2O3(s) ΔH = -1,648 kJ 3Fe(s) + 2O2(g) => Fe3O4(s) ΔH = -1,115 kJ Given the data above, determine the heat of reaction, ΔH, for the reaction: 3 Fe2O3(s) + 3 FeO(s) => 3 Fe3O4(s)

Solved • Nov 14, 2019

Hess's Law

Q. Calculate the enthalpy change for the reaction NO (g) + O (g) → NO2 (g) from the following data: NO (g) + O3 (g) → NO2 (g) + O2 (g) ΔH = -198.9 kJ O3 (g) → 1.5 O2 (g) ΔH = -142.3 kJ O2 (g) → 2 O (g) ΔH = 495.0 kJ

Solved • Nov 13, 2019

Hess's Law

Q. Calculate the enthalpy change for the reaction WO3 (s) + 3 H2 (g) → W (s) + 3 H2O (g) from the following data: 2 W (s) + 3 O2 (g) → 2 WO3 (s) ΔH = -1685.4 kJ 2 H2 (g) + O2 (g) → 2 H2O (g) ΔH = -477.84 kJ

Solved • Nov 13, 2019

Hess's Law

Q. Given the reactions, X(s)+1/2 O2(g)⟶XO(s) ΔH=−605.3 kJ XCO3(s)⟶XO(s)+CO2(g) ΔH=+380.3 kJ what is ΔH for this reaction? (in kilojoules) X(s)+1/2 O2(g)+CO2(g)⟶XCO3(s)

Solved • Nov 8, 2019